In EP 2 152 385 B1, a gas filter with a filter insert is described which can be inserted into a filter housing and has a U-shaped filter element through which the fluid to be filtered flows radially from the outside to the inside. Disposed between the two legs of the U-shaped filter element is the clean space from which the filtered fluid is discharged via an outflow opening, said outflow opening being integrated into a cover panel on the free front sides of the legs.
Moreover, cylindrical filter elements are known which are flowed through radially from the outside to the inside and enclose an axial outflow space from which the fluid is discharged axially. Such cylindrical filter elements are sealed on the front sides by end plates, an outflow opening being disposed in an end plate through which the fluid is discharged axially into a secondary channel.
A cylindrical air filter element is described, for example, in WO 2010/111008 A1. The filtering means of the filter element is embodied as a zigzag-shaped folded filter that is arranged in the manner of a ring, the front sides being interconnected by means of a connecting clip. The connecting clip extends over an arc segment of about 30° and has an air-impermeable wall.
What is generally sought after in filter devices is high cleaning performance with geometric dimensions that are as small as possible.